Acute popliteal thrombus workup leads to discovery of primary peritoneal mesothelioma in the absence of any known asbestos exposure.

A 75-year-old man presented to the emergency department with 1-day history of right lower limb pain and 3-month history of vague abdominal pain. In the emergency department a thrombus was discovered in the right popliteal artery. CT scan of the abdomen and pelvis revealed high-density material in the pelvis, multiple hypodensities on the liver, ascites with omental nodularity, and high-density material along the stomach wall. He underwent thrombectomy and was started on anticoagulation therapy. The core needle biopsy revealed primary omental mesothelioma. There was no history of any known asbestos exposure. He also had to undergo therapeutic paracentesis twice due to abdominal distension. Mesothelioma treatment of carboplatin and pemetrexed was started, and the patient is currently receiving this chemotherapy treatment regimen.

Research priorities in geriatric oncology for 2013 and beyond.

The incidence of cancer increases with advanced age. Unfortunately, there is a significant lack of evidence regarding the safety and efficacy of treatments. The oncology community also lacks information regarding which older patients are most likely to benefit from treatment without undue toxicities. Interventions to lower symptoms and reduce long-term complications from cancer and cancer treatment in older patients are urgently needed. Establishing research priorities in geriatric oncology could help guide researchers and focus efforts on interventions that have the highest likelihood of improving outcomes. The Cancer and Aging Research Group, in partnership with the National Institute on Aging and National Cancer Institute, held linked conferences as part of a U13 grant in September of 2010 and November of 2012, summarising the gaps in knowledge in geriatric oncology and recommending ways to close these gaps. The overall purpose of this review is to highlight the important research priorities in geriatric oncology from the literature and from the previous U13 meetings. More evidence regarding the treatment of older cancer patients is urgently needed given the rapid aging of the population.

Histone deacetylase 1 phosphorylation at S421 and S423 is constitutive in vivo, but dispensable in vitro.

Histone Deacetylase 1 (HDAC1) is a transcriptional regulator associated with proliferation, apoptosis, and tumorigenesis, although its precise cellular role is unclear. HDAC1 was previously characterized as a phosphoprotein where mutation of phosphorylated S421 and S423 resulted in a loss of deacetylase activity and protein association. Here, the role of phosphorylation in regulating HDAC1 function was examined using phospho-specific antibodies. The antibody studies revealed that phosphorylation at S421 and S423 is constant during the cell cycle, under stress conditions, or in the presence of kinase or phosphatase inhibitors. Further, phosphorylation is dispensable for catalysis or protein association in vitro, as revealed by phosphatase studies. Truncation mutants of HDAC1 demonstrated that binding to Sin3A is promoted by S421 and S423 phosphorylation, while interaction with RbAp48 is not. Taken together, the data are consistent with constitutive phosphorylation of HDAC1 at S421 and S423 in vivo, which is dispensable for activity in vitro.

Limited proteolysis of human histone deacetylase 1.

BACKGROUND: Histone deacetylase (HDAC) proteins are associated with cell proliferation, differentiation, apoptosis, and cancer. Specifically, HDAC1 is linked with cell growth, a hallmark of cancer formation. HDAC1 is a phosphoprotein and phosphorylation at S421 and S423 promotes HDAC1 enzymatic activity and protein association. While single and double point mutants of HDAC1 at S421 and S423 appear functionally similar, the evidence suggests that HDAC1 is phosphorylated simultaneously at both S421 and S423 in vivo. Additional experiments are necessary to probe the role of double phosphorylation of HDAC1 at S421 and S423. RESULTS: To characterize HDAC1 phosphorylation at S421 and S423, limited proteolysis of HDAC1 was performed for the first time. HDAC1 degraded without production of discrete fragments. By performing concentration-dependent proteolysis, HDAC1 double point mutants with disrupted phosphorylation at S421 and S423 displayed different trypsin sensitivities compared to wild type HDAC1. Unexpectedly, HDAC1 single point mutants with disrupted phosphorylation at either S421 or S423 demonstrated protease sensitivity similar to the wild type HDAC1. CONCLUSION: Concentration-dependent proteolysis experiments provide evidence that phosphorylation of S421 and S423 individually contribute to HDAC1 function. In addition, the limited proteolysis experiments support a model where associated proteins promote HDAC1 enzymatic activity, reinforcing the importance of protein interactions in HDAC1 structure and function. Finally, because HDAC1 does not display distinct regions of protease sensitivity, the proteolysis studies suggest that HDAC1 comprises inter-related structural regions.